The present invention is directed to an improved process for the drying of wood.
It is known that a rapid and mild drying of wood can be carried out in warm oil under vacuum. Many processes are known for the drying of wood. For example, U.S. Pat. No. 3,560,251 (issued to Hager) discloses the preservation of wood with aqueous solutions followed by drying/coloring of the wood in a heated high-boiling oil under vacuum. U.S. Pat. No. 3,995,077 (issued to Hager) discloses a process where the wood is impregnated with preservation agents contained in an organic solvent followed by the drying/coloring of the wood in hot oil with simultaneous recovery of solvent. U.S. Patent application Ser. No. 125,774 (of Hager) discloses wood preservation with an emulsion followed by drying/coloring of the wood in hot oil. In addition, U.S. Pat. No. 3,811,200 (issued to Hager) discloses a process wherein wet (green) wood is dried in a low boiling oil.
However, it can be a disadvanage for significant amounts of the drying oil to remain in the surface layer of the wood subsequent to the drying process. If too much drying oil remains in the wood, costs are increased as well as the risk of fire and environmental problems. In addition, difficulties can occur with respect to the painting of the wood or use of glue therewith.
In order to overcome these problems, drying oils have been chosen for use with such processes having specific boiling points with the process being carried out at suitable vaccum and temperature. Furthermore, the process can be performed in separate operations to facilitate evaporation of the drying medium from the wood surface.
It is desirable, however, to provide a process for the drying of wood which permits contact of the wood with the drying oil to be minimized and which more effectively removes moisture from the inner portions of the wood.